1. Field of the Invention
This invention relates to an adjustable vibration damper, in particular, for automotive vehicles. The adjustable vibration damper has a cylinder containing a damping fluid, an axially-movable piston rod projecting into the cylinder in a sealed manner, a damping piston fastened to the piston rod, which damping piston divides the cylinder into two work chambers, and a damping valve equipped with a valve seat. The damping valve, by means of an axially movable valve body, controls the effective cross section of a damping passage connecting the two work chambers of the cylinder. The valve body, starting from its pressurized end surface has at least one passage having a constant throttle cross section, which passage runs from the pressurized end surface toward the back side of the valve body, located on the other end. In addition, the valve body also has a throttle passage running in the outflow direction, which throttle passage is controlled by an axially movable, continuously positionable pilot control element.
2. Background Information
German Patent No. DE-PS 37 19 113, which corresponds to U.S. Pat. No. 4,880,086, and German Laid Open Patent Application No. DE-OS 38 35 705 disclose hydraulically adjustable vibration dampers, the damping force of which can be continuously adjusted in both the tension and compression direction. For this continuous adjustment, a damping valve having an axially movable valve body and a valve seat controls the effective cross section of a damping passage. The throttle cross section of the damping passage is thereby controlled by an axially movable, continuously positionable control needle which interacts with the valve body. However, one disadvantage of such an arrangement is that the need for additional flow connections and partitions between the valve body and the pilot control element increases the size of the overall system.